1. Field
Example embodiments relate to a selective catalytic reduction system and a method of controlling a temperature of a reducing agent injection module. More particularly, example embodiments relate to a method of controlling a temperature of a reducing agent injection module for performing an exhaust gas after-treatment of an internal combustion engine and an exhaust gas after-treatment system using the same.
2. Description of the Related Art
A selective catalytic reduction device may be used as an exhaust gas after-treatment device for reducing pollutants existing in an exhaust gas from an engine. The selective catalytic reduction device may include a reducing agent injection module for injecting a reducing agent in a flow direction of the exhaust gas. An engine coolant may circulate through a coolant circulation line connected to the reducing agent injection module to prevent the reducing agent injection module from being overheated due to the exhaust gas of high temperature.
However, when an injection nozzle of the reducing agent injection module is exposed frequently to the exhaust gas of high temperature in a high load work during hot season, the injection nozzle may be thermally deformed to block a nozzle hole. Due to the blockage of the nozzle hole, a proper amount of urea for NOx reduction may not be injected, thereby deteriorating NOx conversion efficiency, and in case of industrial vehicles, causing SCR inducement and an output power limit by On-Board Diagnostics (OBD), and finally an exhaust gas regulation violation and marketability deterioration.